The extraction of silver and palladium from aqueous solutions of hydrochloric acid and nitric acid by means of a water-immiscible organic solution of a tertiary phosphine sulfide is known in the literature; see, for example, Hitchcock et al, Anal. Chem. 35, 254 (1963), Elliott et al, Anal. Chem. Acta 33, 237-246 (1965), Blednor et al, 8b, Nauk Tr. Krasnyansk, Inst. Tsvet. Metal 4, 180-186 (1973), Cattrall et al, J. Inorg. Nucl. Chem. 40, 687-690 (1978) and Mitchell et al, J. Radioanal. Chem. 43, 371-380 (1978). The extraction of these metals from aqueous sulfuric acid is not reported. However, such extractions have a high degree of unpredictability. For example, it is known to extract iron from chloride solutions and uranium from nitrate solutions with tri-n-octylphosphine oxide, but neither metal is extracted from sulfate solution; see ONRL 61-2-19, Feb. 1961. Moreover, the separations reported do not relate to the recovery of metals from ore leachates, as would be practiced by the metal recovery industry. Finally, with common diluents, such as kerosene, precipitation of the complexed metal and collection thereof at the phase boundary can sometimes be a problem. Thus, there is not presently available a suitable economical method for the industrial recovery of silver or palladium from aqueous sulfate leach solutions.